The name derives from their bipedal form (they hop like tiny
kangaroos) but the resemblance is purely visual: kangaroo rats
and kangaroos are only distantly related, as both are mammals.
Twenty one species are currently recognized. Size varies from
100 to 200 mm, with a tail of equal or slightly greater length;
weight can be anywhere between 35 and 180 grams.

The
most distinctive feature of the D. merriami is their very
long, hind legs. Like the jerboas of African and Asian deserts
and the hopping mice of outback Australia, D. merriami have
highly developed hind legs, live in deep burrows which shelter
them from the worst of the desert heat, and rarely drink water.
Instead, they have a highly water-efficient metabolisim (their
kidneys are at least four times more efficient than those of
humans), and manufacture water by chemical breakdown of their
food.

Their diet includes seeds, leaves, stems, buds, some fruit,
and insects. D. merriami use their burrows and
buried caches nearby to store food against the possibility of
bad seasons.

D.
merriami
are found in arid and semi-arid areas which retain some grass
or other vegetation, in NW Nevada and NE California to Texas
(USA), south to Baja California Sur, N Sinaloa, and the Mexican
Plateau to San Luis Potosi (Mexico).